Paint prep question, HELP!

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downtofish

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I'm stripping a 12 foot vhull at the moment down to bare aluminum. The boats old and I'm useing a sanding wheel to get down to bear metal which means it will be comepletely uncoated till spring when its warm enough to paint. Is this a bad idea ? -- Should I clean it with alumaprep 33 then coat it with the alodine stuff before I let it sit for three months ?? or am I ok just letting it sit open for 3 months ? it already has some pitting, so we are not talking about anything fancy here. I will be steelflexing the bottom and Grizzly gripping the topside/sides in spring for my topcoat.
 
It MUST be coated with something. :arrow: In a day or two, the bare aluminum oxidizes and forms a clear almost non visible coat that prevents the paint from gripping when painted.

If you let it stay like that for months, you have to use a aluminum oxide remover prior to painting (primer and paint) or resanding the entire hull.... ask me how i learned! 12ft is peeling. #-o

I recommend you to put the primer before left it for three months. That way, you only lightly sand and paint the color coat. 8)
 
If you decide to primer for storage, use a primer like red oxide or equivalent that does not absorb moisture. Just look at cars that only use the grey metal primer without paint and look at the rust that starts forming through the primer.

When I bought my 20 plus year old aluminum boat it had large pits on the bottom side. I ground them down and painted using Interlux underwater primer and paint. Kind of expensive but was worth it.

Good luck!
 
Use self etching primer...if you search the forum you will find that is the only recommended primer and is necessary for adhesion to bare aluminum.
 
If you're going to use primer, be sure that is is zinc chromate, as this is the only type of primer that will stick to aluminum.

It's best to use some phosphoric acid to etch the aluminum, then rinse and dry, before priming. If it has sat for any length of time after being sanded, etched, etc, you have to remove the layer of aluminum oxide for proper adhesion of coatings.
 
While Zinc Chromate may be a /better/ solution than Self Etching, I don't agree with the statement that it is the only primer that will stick to aluminum. From all the reading I have done there are quite a lot of folks using self etching and being quite happy with the results. I used it on mine and the end bond has been quite good so far.

I have read zinc chromate to be the best in a salt water application...

Self Etching primer is made for bare aluminum...seems odd to make a statement that ZC is the ONLY primer that sticks...
 
Ok I also need to give my boat a painting.
Where is the most cost effective place to buy zinc chromate primer? And what paint should I put on the interior and exterior?
 
great info. Although I think I asked a question I already knew the answer to! lol I'm going to let it sit. By letting it sit I'll have to deal with oxidizeing.... no biggie since I plan on allumaprep, alodine, then primeing, then painting. Primeing might be overboard, As far as I've read I can steelflex right over the alodine coating with excelent results??
 
Mnfishingbum said:
Ok I also need to give my boat a painting.
Where is the most cost effective place to buy zinc chromate primer? And what paint should I put on the interior and exterior?

You can buy ZC primer in spray cans, or, you can buy it by the quart. Check West Marine or some other boat supply catalog. It's made by Interlux.

For doing an entire boat, I would say at least 1 qt would be needed. The 1 quart can also comes with a small can of activator. You mix the two together, then shoot it through an HVLP gun. Once it's mixed, as with other 2 part coatings, it must be used before the pot life expires.

However, when applying ZC primer, you don't have to put on a thick coat as you would with other primers. You just want to fog over the surface with a thin layer
 
Jdholmes said:
While Zinc Chromate may be a /better/ solution than Self Etching, I don't agree with the statement that it is the only primer that will stick to aluminum. From all the reading I have done there are quite a lot of folks using self etching and being quite happy with the results. I used it on mine and the end bond has been quite good so far.

I have read zinc chromate to be the best in a salt water application...

Self Etching primer is made for bare aluminum...seems odd to make a statement that ZC is the ONLY primer that sticks...

There probably are other primers that work, but at the factory, when they paint aluminum boats, 9 times out of 10, they use ZC primer, in case the boat is used in saltwater. The rate of oxidation is so severe in saltwater, there are very few coatings that will stick to aluminum.

If you ever sand through the paint layers on a johnboat, you can see there is a layer of green or yellow primer underneath. This is zinc chromate.
 
Absolutely. Makes sense...Manufacturing plants don't know the envorinment it will be in, so they should take steps to ensure it will be ok. Folks living inland know that our boats will never see salt water, so we can take the other route.

I definitely agree it seems to be the better option if you can.
 
I would think any oil based paint would be adequate, but it would be best to use something that is rated for a marine application for maximum durability.

On my boat, I used Interlux "Brightside" paint for the black exterior, and for the Hatteras off-white interior.
 
depending on kind gloss look you want also flexability !and how much you want to spend on paint !trackter suppliespaint work well on salt app. we paint ,airboats that live insalt most of there lifes !not lastin g bottms because they are running rock ,logs and such !lets fish salt
 

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